According to the prior art, in order to project a very large size of image, since a conventional projector cannot project a sufficiently bright image when a very large screen is used, several projectors are implemented such as is illustrated in FIG. 1A. Thus, digital projectors 14 to 16 each project an image onto the same screen 10. The transmitted beams 11 to 13 associated with each of the projectors 14 to 16 are adjacent to one another. Electronic processing means, that are relatively complex, allow the separation between the three projected images to be rendered invisible, as is illustrated in FIG. 1B. This technique has the drawback of not allowing a uniform brightness of the three images 17 to 19, especially when the lamps of the projectors 14 to 16 begin to age. There may also be color differences on the projected images.